BERLIN, Aug 27 (Reuters) - Germany's Angela Merkel told President Vladimir Putin by phone on Wednesday that reports of a new Russian military incursion into Ukrainian territory had to be cleared up, a spokesman for the chancellor said in a statement.

"The latest reports of the presence of Russian soldiers on Ukrainian territory must be explained," said Merkel's spokesman Steffen Seibert. "She emphasised Russia's major responsibility for de-escalation and watching over its own frontiers."

Kiev accused Russia of launching a new military incursion over its eastern border on Wednesday. Russia's defence ministry made no immediate comment, but Moscow denies sending weapons and soldiers to help pro-Russian separatists in eastern Ukraine. (Reporting by Stephen Brown)